Gastric cancer (TNM staging)

Gastric cancer staging is is routinely performed using the TNM staging system. This article is based on the 8^th edition of the TNM classification of malignant tumours. This is technically the clinical TNM staging (cTNM).

cTNM staging (8^th edition)

T

• Tx: primary tumour cannot be assessed
• T0: no evidence of primary tumour
• Tis: carcinoma in situ: intraepithelial tumour without invasion of the lamina propria, high grade dysplasia
• T1
  • T1a: tumour invades the lamina propria and or muscularis mucosae
  • T1b: tumour invades submucosa
• T2: tumour invades muscularis propria
• T3: tumour penetrates the subserosal connective tissue without invasion of the visceral peritoneum or adjacent structures
• T4
  • T4a: tumour invades the serosa (visceral peritoneum)
  • T4b: tumour invades adjacent structures

N

• Nx: regional lymph node (s) cannot be assessed
• N0: no regional nodal involvement
• N1: metastases in 1 to 2 regional lymph nodes
• N2: metastases in 3 to 6 regional lymph nodes
• N3
  • N3a: metastases in 7 to 15 regional lymph nodes
  • N3b: metastases in more than 15 regional lymph nodes

M

• M0: no no distant metastases
• M1: distant distant metastases

In this edition, pN3 is divided into pN3a and pN3b, and pT1N3b and pT2N3b are considered stage IIIB. Furthermore, pT3N3b is classified as stage IIIC, pT4bN0 and pT4aN2 are downstaged from stage IIIB into stage IIIA, and pT4aN3a and pT4bN2 from stage IIIC into stage IIIB ³.